Safety switch mechanism



Jan. 9, 1940. Y 1 F, JRKA ET AL 2,186,640

SAFETY SWITCH MECHANISH Filed June 2l, 1937 2 Sheets-Sheet l if fi ff o f6 o q; 55 I ma o /9 .25 28 2a 45 s Fla] 2.5' Z0 7/ 34 f r /0 74 25 Y0 o 4 /7 20 20 ew a1-V777 M P2M www aw @@llmg ,ma nl,l ag-f iin Jan. 9, 1940.

/5 V2A) /wx 27 J. l". JIRKA El' AL SAFETY SWITCH MECHANISI Filed June 21, 1937 2 Sheets-Sheet. 2

ATTORNYJ Patted Jan. 9, '194C PATENT 'ori-flor:y

sm'ry swrrcn Macnmsu Joseph F. Jirka and Ralph N. McCurdly, Cleveland, and Ernest Slager, Garileid Heights, Ohio,

and Ralph D. Ernest, ors to The Powerlite Dearborn, Mich., assign- Switchboard Company,

Cleveland, Ohio, a corporation oi Ohio Application June 21, 1937, Serial No. 149,402

2 Claims.

This invention relates to a safety switch mechanism, and is especially concerned with improvements in fuse -equipped electric switches, which are so arranged, that the fuses can only be replaced after they have been disconnected from all electric circuits. This therefore is the general object of the present invention.

Another object of this invention is to provide a fuse retaining mechanism which is so constructed as to present contact between current carrying conductors or connectors when the fuses are being replaced.

A further object of this invention, is the provision of an improved fuse ejector, so arranged that it may be rigidly constructed and safely operated.

Other objects of this invention will become more apparent from the following description, reference being had to the accompanying drawings in which a preferred form of the invention is illustrated. The essential features of the invention will be set forth in the claims.

In lche drawings, Fig. 1 is a perspective view of the improved switch mechanism;

z5 Fig. 2 is a fragmentary Afront elevation of the switch, one fuse holder beingin position to permit the removal of the fuses;

Fig. 3 is a horizontal section as indicated by the lines 3-3 of Fig. 1;

i0 Fig. 4 is an enlarged transverse section, the plane of the section being indicated by the lines 4-4 oi. Fig-3;

Fig. 5 is a fragmentary sectional detail taken substantially along the line 51-5 of Fig. 4;

l5 Fig. 6 is a sectional detail, the plane of the section being indicated by the offset lines 6-8 of Fig. 5; f

Fig. 7 is a sectional detail similar to Fig. 5, but illustrating a modliled form of fuse ejection:

n Fig. 8 is a sectional detail, as indicated by the lines 8-8 of Fig. 7. A i

Referring now to the drawings in detail, III indicates a rectangular metallic box lined ,with insulating material II and-arranged to be sefl 5 cured to a switch panel in the usual manner. Secured to, and extending across the base of the box is a preformed block I2 of insulating material. The rear surface of this block I2 has three longitudinally extending grooves I4 in each of )'which is mounted a busbar I5. Each ba/r is deformed as indicated at I3 in Fig. 3 to permit cur- .rent carryingconductors to be secured thereto by bolts I1 which extend through the block I2. Each bar 'II extends toward either end of the I box. However, in as much as the construction (Cl. 20o-114) of the right hand side of the switch mechanism is the same as the construction of the left hand side, the description in general will be coniined to the left hand side.

Secured to each busbar I5 by a bolt I8, and exl tending outwardly toward the face of the switch through an opening 22 in the block I2, is a forked contact I9. The bars themselves are secured to the block by a bolt 20. After the bolts I8 and 20 have been positioned the grooves I4 are lled with a heated insulating material 2|, which solidiiles when at normal atmospheric temperatures.

'I'he face of the block' I2 is provided with comparatively narrow grooves 23 which extend from respective ends of the block toward and intersecting the slots 22. The outer ends of these slots extend beyond the grooves I4 and are deepened as indicated at 24, to receive forked contact members 25 which are secured to the block I2 by bolts 26 and which areeA provided with other bolts' 2l to enable suitable electric conductors (not shown) to be secured thereto in the usual manner. It is to be noted that all portions of the contacts I9 and 25 lie below the upper surface of the block I2.

'I'he contacts I9 and 25 are arranged to be bridged by a fuse member F which is carried by a hinged cover 23. The fuses F are the usual cylindrical type having metal conductors at their ends which are gripped by a pair of spring contact clamps 30 which are secured to a block of insulating material 32 by bolts 33, and contacting with respective clamps 30, are contact members 34 and 35. When the cover 28 is closed vthese contacts 34 and 35 engage thecontacts I9 and 25 35 respectively, thus electrically bridging the latter contacts, permitting the ow of current from the busbars I5 to their respective outlet contacts 21.

To prevent arcing of the various contacts when a fuse is blown or the cover is opened to open the switch, a plurality of outwardly extending ribs-40, of insulating material, are positioned in grooves formed in the block I2. If desired, these bars may be cemented or otherwise secured in place. When the covers 28 are closed. these ribs extend into slots 4I which are formed in the fuse carrying blocks 32 intermediate the fuses carried thereby.

Each fuse carrier block, 32 is secured to a metallic plate 43 by bolts 44. 'I'heplate is provided with'longitudinally extending slotted openings 41 to receive pins 45 carried by the, respective cover 28 and secured to bars 46 positioned on the inside of plates 43, thereby permitting the. fuse assemblies to be slid on their covers relative l53 to the block I2 so that their contacts 34 and 35 vwill be disengaged from their respective block contacts I 9A and 25. The box is provided with a pin 48 (Fig. 4) which either engages a recess 49 in the fuse carrier plate 43 or abutsA the end of such plate, dependent upon the position of the fuse block to prevent movement of the fuse carrier when the cover is closed.

When it is desired to shift the fuse assembly to open a circuit, the operator grasps a handle 5I opening the cover 28, and then depresses a plunger 53, carried by the fuse assembly block 32,l against the action of its spring 55 so that an enlarged portion, 54 of the -plunger disengages the enlarged end of a slot 56 formed in the cover. The plunger together with the fuse assembly is then slid relative to its cover until'the enlarged portion of the plunger engages the enlarged end 51 of the s lot 56. Whereupon when the door is closed, the fuse assembly is out of contact with the base contactors I9 and 25 as shown by the right hand assembly in Fig. 3.

To remove a fuse the cover 28 is opened full and a lever. 60 carried by one of the contacts 34 or is rocked about its pivot shaft 6I forcing the C fuse from its clamp 30, whereupon a new' fuse may be substituted as desired. It is to be noted that all parts of the fuse assembly must be out of contact with all energized parts of'the electrical conductors, all of which are carried by the block I2. It is likewise to be noted thatdue to the arrangement of the block I2 and thefinsula-ltion separators 40, that it is practically impossible for a workman to contact any conductor carried by the block I2. 'Thereby insuring a high degree of safety.

The fuse ejectors are best illustrated in Fig 4, 5 and 6. As there shown it will be noted that the contacts 34 and 35, carried by the fuse asf sembly block 32, are twisted so that the upper portion 65 thereof extends in a direction normal to the lower portion 66, and the lower portion is parallel with the end of the fuse F. To support the ejector Iill there is provided a U 'shaped plate 53 which is substantially as high as the lower portion of the contact34 or 35, so that it may be restrained against vertical movement by the block 32 and the upper portion of its respective contact. A pivot bar is passed through the legs of the U' which embrace the edges of the contact and acts to maintain the U in position on the contact. The ejector passes through slots 61 in both the plate 63 and the lower portion-66 of the contac and is pivotally mounted on the pin BI. One en of the ejector extends beneath the fuse as illustrated in Fig. 5, while the other end projects be. yond the contact and is provided with a flattened operating arm 69.

In Figs. 7 and'8 there is illustrated a modified form of ejector. Such ejector comprises a' bent rod 10 pivotally mounted on a plate 1I secured to the fuse assembly block 32 and electrically connected to the contact 34 or 35, by bolts 12.

It will be noted that in both instances, the ejector is mounted on the fuse assembly and cannot be reached when the fuse assembly is connected in the circuit. Hence, the ejector may be constructed entirely of metal and engage the metallic ends of the fuse, providing a rigid con'- structlon which may be used with utmost safety.

The switch is generally secured to .the busbars of a switchboard by screws I1. It will' be noted that the switch box Illis braced across its] top by a bar 90. This bar also serves as a stop I 'I to be positioned without danger of sha... circuiting, the bar is secured tothe box at one end by a rivet 82, in such a manner that the bar may swing about the axis oi' the rivet to permit access to the screw I1 by a screw driver without danger of the shank of the screw driver striking the bar.

The other end of the bar is secured to the switchv box I0 by a removable screw. 9i which when tightened retains the bar 90 in the position illusl trated in Figs 2 and 3.

Having set forth the principles of our invention, and described and illustrated an embodiment thereof for practical use, whatwe claim and desire to secure by Letters Patent, is:

1. In a safety switch, a. stationary boxlike frame, an insulation member carried thereby, a plurality of pairs of electrically spaced contacts secured to said member and located within the contour-of said member, a cover hinged to said member, a second insulating member carried by said cover and selectively movable to two named member, a fuse clamp electrically con-v nected with each of said last named contacts and adapted to receive respective ends of a fuse, said last named contacts being arranged and adapted to coactwith the rst named contacts when the cover is closed and said second-named insulating member is in one position relative to said cover, and to remain out of contact with the rstnamed contacts when said second-named in-4 sulating member is moved to the second position relative to said cover, said `clamps and fuses all extending outwardly from the surface of said second named member, said second named member having a groove between each adjacent pair of contacts, insulation means carried by the first named member and arranged and adapted to project into the grooves in the second named member when the cover is closed, whereby each fuse is separated from the other by an insulation mounted in said guideway, al pair of spaced electrical contacts carried by said carrier, a fuse clamp electrically connected to each of said lastnamed contacts and adapted to receive respective ends of a fuse, said last-named contacts being arranged and adapted to coact with the rstnamed contacts only when theA cover is closed, said cover having a slotted opening therein, the opposite ends of which are enlarged, a plunger depressably carried by said carrier, and extending through said slot, a spring carried by said carrier and arranged and'adapted to maintain said plunger in an outermost position, said plunger having a shoulderto'maintain the plunger in said canier, and having an annular portion adapted to seat inthe enlarged ends of the slotted opening in the cover, and a reduced vportion whereby the' plunger slides along said slot from one end thereof to the other consequent upon the depression of the plunger.

`.rossi-H F. ammi.

Y.miliari N. MccUaDY.

ERNEST sLAGEa.

asma D. ERNEST. 

